I had some similar problems some time ago.
You should try this.
first of all, disable de browscap.ini in the php.ini
Then check out the httpd.conf of the apache: I used:
ScriptAlias /php4/ "C:/php4/"
<Directory "C:/php4/">
AllowOverride None
Options ExecCGI
</Directory>
Action application/x-httpd-php4 '/php4/php.exe'
AddType application/x-httpd-php4 .php
AddType application/x-httpd-php4 .php3
make sure to change the path´s to your needs, and check the browscap.ini matter.
Alejandro